Many power sources are capable of providing a limited power level. Such power sources may be called power limited power sources or power limited sources. When such power sources are used to power devices that have a high peak-to-average power consumption, the average power output of the device can be severely limited if the peak power draw must be kept below the power supply limits of the limited power source.
An example of a device that typically has a high peak-to-average power consumption is an audio speaker. In modern computer systems, and in many other devices that include a speaker, it can be desirable to power speakers from a limited power source.
For example, many computer users prefer to use speakers that receive both an audio signal and power through a single connection such as a USB port. A USB port can provide only 2.5 watts of power and is an example of a limited power source.
In some audio systems, it is desirable to transmit both an audio signal and power to a speaker across an Ethernet cable or other connection that is capable of carrying only a limited amount of power. An Ethernet cable can carry only a limited power level, typically due to current limitations. The length of an Ethernet cable will limit the power delivered to a device coupled to a power source through the cable. Typically, a 100 m Ethernet cable (with poor feed resistance) may be able to deliver about 13 watts of power to a device. The power source and Ethernet cable are an example of a limited power source that is unable to supply more than a limited amount of power. In this case, the power limitation is due to the Ethernet connection between the power source and the device.
It is desirable to provide a power supply for use with power limited sources to improve the performance of devices powered by such sources. It is also desirable to provide an audio amplifier including a power supply for use with limited power sources.